Rolling mill work roll assemblies

ABSTRACT

A method of manufacturing a rolling mill work roll assembly which comprises a work roll held in position on a hollow shaft member by the shaft member being in a stressed condition to exert radial loading and preferably also axial loading on the work roll. The grip is sufficient to transmit normal driving torque. The method comprises axially stretching the shaft by hydraulic pressure means acting within the hollow, and this causes reduction of the diameter of the hollow shaft to permit insertion and removal of the shaft into and from the work roll bore. The hollow shaft has a larger diameter than the work roll bore when not so stretched. After insertion the hydraulic pressure is removed and the shaft assumes the above stressed condition.

United States Patent [191 Oxlade [451] Aug. 27, 1974 ROLLING MILL WORKROLL ASSEMBLIES [75] Inventor: Roy Ronald Oxlade, London,

England [73] Assignee: The British Iron and Steel Research Association,London, England [22] Filed: Sept. 6, 1973 [21] Appl. No.: 394,882

Related US. Application Data [62] Division of Ser. No. 881,801, Dec. 3,1969.

[30] Foreign Application Priority Data Dec. l0, 1968 Great Britain58650/68 [52] US. Cl. 29/l48.4 D, 29/452 [51] Int. Cl B23p 11/00, B2ld39/00 [58] Field of Search 29/l48.4 D, .452, 148.4 R,

[56] References Cited UNITED STATES PATENTS 3,577,6l9 5/1971 Strandel29/l48.4 D

3,633,259 [/1972 Nikanen 29/l48.4 D

Primary Examiner-Thomas l-l. Eager Attorney, Agent, or Firm-Sughrue,Rothwell, Mion, Zinn & Macpeak ABSTRACT A method of manufacturing arolling mill work roll assembly which comprises a work roll held inposition on a hollow shaft member by the shaft member being in astressed condition to exert radial loading and preferably also axialloading on the work roll. The grip is sufficient to transmit normaldriving torque. The method comprises axially stretching the shaft byhydraulic pressure means acting within the hollow, and this causesreduction of the diameter of thehollow shaft to permit insertion andremoval of the shaft into and from the work roll bore. The hollow shafthas a larger diameter than the work roll bore when not so stretched.After insertion the hydraulic pressure is removed and the shaft assumesthe above stressed condition.

4 Claims, 4 Drawing Figures r I 403318 42 32 21 so 1 ROLLING MILL WORKROLL ASSEMBLIES This application is a division of my application Ser.No. 881,801 filed Dec. 3, 1969.

This invention relates to methods of manufacturing work roll assembliesfor use in rolling mills. Particular applications for such assembliesmay be found in two high or in four or more high rod or bar mills,embodiments of the latter being disclosed for example in US. Pat. Nos.3,587,267; 3,611,531 and 3,613,428.

It is generally desirable that mill work rolls be removable so that theycan be exchanged for different rolls to permit a variety of rod or barsizes and shapes to be rolled on the same mill and also to permit wornrolls to be replaced. The work rolls are accordingly removably carriedon roll drive shafts which are rotatably mounted and driven in the millframe. The mounting of the roll on the shaft so as to facilitate theready removal thereof whilst still enabling the roll to withstand theheavy rolling loads without damage to the mounting or shaft is acontinuing problem for the mill designer.

An object of the invention is accordingly to provide a method ofmanufacturing a work roll assembly so that it is readily removable fromthe drive shaft.

According to the present invention there is provided a method ofmanufacturing a rolling mill work roll assembly, said assemblycomprising a hollow shaft member which is coaxially secured to or formedintegrally with a work roll drive shaft which extends co-axially in abore of a work roll, said work roll including an annular member formedto define a rolling groove or surface of the work roll, said methodincluding applying a force axially to stretch said shaft member to causesufficient diametrical reduction thereof to permit insertion thereofinto its assembled position in said work roll bore, said shaft memberwhen not so stretched having a diameter too large to permit suchinsertion, and removing said applied force to cause the shaft member toassume a stressed condition in which it exerts radial loading outwardlyon said work roll to provide radial location of said work roll withrespect to said shaft member.

In preferred embodiments of the invention the annular member issupported on both sides by sleeve members. Accordingly the ring membermay be of, e.g. tungsten carbide and the sleeve of, e.g. steel. Thetungsten carbide provides a long, accurate roll groove life, whichresists wear, thermal shock and rolling fatigue. The roll groove thushas the advantages of tungsten carbide but the roll as a whole is not soheavy or as expensive as a solid tungsten carbide roll would be.Moreover if the annular member is damaged, it is readily replaceable,without the necessity of replacing the steel sleeve member. A damagedtungsten carbide solid roll would have to be scrapped as a whole. Theprovision of a composite roll in this manner which can readily bedis-assembled, also provides thefadvantages of ease of handling, and thestorage bulk of the mill inventory of different groove size rollingmer'ribers is reduced. Finally the composite roll can, in some forms, bemore adequately cooled in use.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal section of a work roll which forms part of anassembly according to the invention for use in a four or more high rodor bar mill,

FIGS. 2 and 3 are longitudinal sections of .work roll assembliesaccording to the invention, also for use in a four or more high mill,and 1 FIG. 4 is a longitudinal section showing embodiments of anassembly for use in a two high mill.

FIG. 1 shows a composite work roll fabricated as first and secondseparable supporting sleeve parts indicated generally at 10 and 11, anda ring or sleeve member 12 provided with a single circumferentialrolling groove 13. The sleeves have axial bores 14 and 15. The firstsleeve has an outer end portion presenting a recess 16 for a purpose tobe described below. The inner end portion of the first sleeve presentsan annular seat 17 accurately perpendicular to the roll axis, and avestigial spigot 18 radially inward of the seat 17.

The second sleeve 11 has an outer end portion adapted to locate the rollaxially and radially on a work roll shaft as will be explained below.The inner end portion of the second sleeve presents an annular surface20 perpendicular to the roll axis, and a frusto conical spigot 21radially inward of the seat 20. Spigot 21 converges away from the sleeve11 and terminates in an annular face 22 opposed to an annular face 23presented by the end face of the spigot 18.

The ring member 12 has a constant cross-section in the general shape ofa trapezium. The parallel annular side faces 30, 31 are perpendicular tothe roll axis. The axial length of the ring is equal or marginally lessthan the summed axially lengths of spigots l8 and 21.

The inner surface of the central aperture of the ring 12 is a frustoconical surface 32'over the major portion of its axial length, the coneangle, axial length and datum diameter of surface 32 being substantiallyequal to the corresponding external dimensions of spigot 21. Theremainder of the inner surface of the central aperture of ring 12 is acylindrical surface 33 substantially equal in diameter and axial lengthto the diameter and axial length of spigot 18.

Two diametrically opposed pairs. of registering axially directedkey-ways 40, 41 are provided, the key-ways of each pair being formed inthe inner surface of the ring 12 and in the outer surface of the spigot2l.'A key member 42 is shaped for sliding movement into each said pairof key-ways.

The outer end portion of the second sleeve 11 is constructed in the samemanner as the equivalent end portion of the work roll particularlydescribed in and with reference to FIGS. 2 and 3 of the drawings of ourcopending Pat. application Ser. No: 52086/67. Briefly the end portionpresents an axial recess 50 shaped to receive a work roll shaft spigot,an annular seating surface 51 radially outward of the recess 50, and acurved wall key member 52 extending circumferentially of the part 11 toslightly less than 180 of the roll circumference. Recess 50 locates theroll radially on the shaft spigot, surface 51 locates the roll axiallyon the shaft seat, and key member 52 mates with a key-way and anoptional wedge associated with a work roll shaft substantially toprevent backlash between the roll and its shaft.

In use the three parts l0, l1 and 12 of the work roll, and key members42, are assembled as shown in the drawings. The work roll is thenmounted to a work roll shaft by means of a hydraulic hollow bolt (notshown) extending from within an axial bore in the shaft and throughbores 14 and 15 of the work roll. A nut is threaded on the end of thebolt. A radial face of the nut bears against the annular face within therecess 16 of part 10. When the nut has been tightened on the bolt andthe bolt has been de-pressurised to relax into a state of considerableaxial tension, it will be seen that the parts 10, 11 of the roll areurged axially together into pre-loaded engagement. The annular seat 17on part provides axial support and location in one axial direction forthe ring shape part 12. Support and location for part 12 in the otheraxial direction is provided basically by tapered spigot 21 engagingtapered surface 32 of ring 12. This latter engagement also providesradial support and location for ring 12 on part 11. Parts 10 and 12 arelocated radially by the engagement of vestigial spigot 18 and surface33. Backlash between ring 12 and part 11 which is the driven part of theroll is substantially prevented by friction assisted by key members 42,which also serve to drive the ring 12.

The support parts llland 11 would normally be of steel and the ringmember 12 of tungsten carbide. An advantage of this embodiment is thusthat the ring member 12, which is the part containing the groove 13 andthus most subject to wear in use, can be made of considerably harder andlonger lasting material than the remainder of the work roll. Expense ofmaking the whole roll of hard wear resistant material is thus avoided,and similarly it may be possible to achieve a work roll whose supportparts 10, 11 and ring 12 wear at substantially the same rate, althoughpart 12 is subject to greater wear in use. Moreover the roll isseparable into parts and thus a worn ring can readily be replaced. lnaddition the ring 12 can readily be replaced by a ring defining adifferently shaped rolling groove 13. In another embodiment ring 12 maybe provided with two or more rolling grooves.

Furthermore tungsten carbide is approximately twice as heavy as steel,so the weight of a solid tungsten carbide roll would render the rolldifficult to handle. Finally, parts 10 and 11, which in use roll on aback up roll surface, could be formed of a fatigue resistant steel notsuitable for roll groove material but with longer life when serving onlyto define a back up work roll contact surface.

If necessary, instead of or in addition to keying, the roll part may beglued or brazed together and/or the roll may be glued or brazed to thedrive shaft.

Referring now to FIG. 2 there is shown a longitudinal section of a workroll assembly for a four or more high rod or bar mill comprising a workroll mounted on a hollow shaft member 60 secured to a drive shaft 61.The work roll comprises a ring member 62 defining a rolling groove 63.The ring member 62 is axially l0- cated and supported by two sleevemembers 64, 65. The three members 62, 64, 65 are mounted on hollow shaftmember 60 which has a threaded end portion 66 received in a threadedrecess 67 in the end of the drive shaft 61. A head flange 68 on thehollow shaft member engages sleeve 64, and an annular seat 69 on the endof shaft 61 engages sleeve 65. Consequently flange 68 and seat 69provide axial location in both directions for the work roll.

The member 60 serves as a form of hydraulically expansible bolt. In itsunassembled unstressed state its diameter is slightly greater than thediameter of the bore through the parts of the composite work roll. Inorder to insert the member 60 through the bores, the member 60 isaxially stretched by hydraulic pressure means acting internally thereof.The axial stretching is accompanied by a diametrical shrinkagesufficient to permit the three roll parts to be mounted on the member60. The member 60 is then threaded into the drive shaft 61 and tightenedthereon by simple mechanical means, this is, no special effort is madeto tighten it very securely. The hydraulic pressure within the hollow isthen released, thus causing the member 60 to expand in diameter, so faras it is able, and to shrink in axial length, to assume a stressedcondition.

The diametrical expansion causes the member 60 to exert substantialradial loading on the work roll members 62, 64 and 65 whereby to locatethem radially (provided their relative bore diameters are correctlychosen in relation to the bolts diameter); and the axial shrinkagecauses the member 60 to exert substantial axial loading on the work rollmembers by means of flange 68 and seat 69.

It should be noted that the threaded portion on the head of the hollowshaft member 60 serves for attachment of a valved pressure devicethrough which the hydraulic pressure fluid is forced to build up on thehead of a plunger. The tail of the plunger engages the inner end of thehollow, whereby to cause the hydraulic pressure to act directly tostretch the bolt and permit its diameter readily to shrink as described.When in use the hollow in the bolt is protected from dirt by a dust capshown e.g., at 88 in FIG. 3.

If desired additional location can be afforded by keying means, such asmating spigots, on the roll members and the drive shaft, one such beingshown schematically at 70.

The torsional drive of the roll is transmitted by virtue of acombination of the axial clamping force and the radial grip whicheffectively also comprehends circumferential location by friction. Thedrive from the drive shaft 61 to the roll is provided by the key 71,similar to that described in relation to FlG. 1. If desired two or moresimilar keys spaced circumferentially may be used. The torquetransmission capability can be enhanced, if desired, by keying meansacting between the assembled parts, e. g., knurling the outer surface ofthe member 60, providing keys between the roll sleeves, or by glueing orbrazing mating surfaces of the roll sleeves, or the outer peripheries ofthe three members 62, 64 and 65 can be provided with mating noses andrecesses.

Referring now to FIG. 3, two embodiments are shown in the upper andlower halves of the drawing respectively. In each embodiment a hollowshaft member acts in a similar manner to the hollow shaft member 60described in relation to FIG. 2, except that in this case it is formedintegrally with the drive shaft 61. Consequently, it is not possible toplace the work roll sleeves 81, 82 and 83 on the hollow shaft memberfrom the right hand end thereof. In the upper half of the figure thevalved pressure device, which threads on the head 84 of the hollow shaftmember, is of larger diameter than the bore of the sleeves 81, 82 and83. Thus the sleeve cannot be mounted from the left hand end when themember 80 is pressurized.

To solve this difficulty the hollow shaft member is either given agradual taper (not shown) or is stepped as shown at 85 and 86. Thesleeves are of appropriate internal diameters as shown. To assemble theassembly, the sleeves are placed on the unpressurized unstressed member80 onto diameters displaced one step to the left of their finalposition. The valved pressure device can then be attached to threadedportion 84 and the member pressurized. The sleeves can then be moved onestep to the right onto their final positions as shown, and the bolt thendepressurized to assume a stressed condition to provide location asdescribed above in relation to FIG. 2. In this case a nut 87 or otherlocking device serves the purpose of flange 68.

In the lower half of FIG. 3 the inner diameter of the hollow shaftmember 80 is threaded at 89 and the valved pressure device for use inpressurizing the bolt is dimensioned to be wholly of less diameter thanthe bores of the sleeves. Consequently the sleeves can then be placed inposition on the member 80 over the pressure device, thus avoiding theneed for steps 85 and 86.

Referring now to FIG. 4, there is shown a work roll assembly for a twohigh mill, and four embodiments are partly illustrated in this Figure.

In the first embodiment a plurality of work roll grooved rings 90 arespaced along a hollow shaft member 91 and are maintained in position,radially and axially, simply by the stressed condition in member 91exerting sufficient radial loading thereon. The torque transmissioncapability can be enhanced if required by knurling the member 91 orproviding flats or keys between the ring bore and the member 91, or byglueing or brazing the rings to the member 91. Cooling of thisembodiment would be very efficient since cooling fluid could penetratethe annular grooves between adjacent rings 90.

The hollow shaft member is shown as formed integrally with a drive shaft92 and is supported for rotation on two chocks 93, provided withsuitable roller bearings 94. The chocks and member 91 are axiallymutually located by virtue of the slow taper of shaft portions 95, andby end nuts 96.

FIG. 4 also shows, in its lower half, rings 90 spaced by spacing rings97. The sequence of alternate rings 90 and 97 are axially clamped andlocated between a flange 98 on the member 91 and a nut 99, which istightened before de-pressurizing of the hollow shaft member 91 in asimilar manner as described before. In this embodiment, of course, theradial loading by member 91 is not essential, since the axial loadingand location can be sufficient to transmit the necessary torque.

This Figure also shows rings 90 spaced by spacing rings 100 which aretrapezium shaped in cross-section and taper inwardly, the taper matchingouter bevels 101 on the rings 90. Spacing rings 102 are also shown,which are trapezium spaced and taper outwardly, the taper matchingundercut bevels 103 on the rings 90. The rings 100 are usuallypreferable since their hoop stress in use exerts compression on therings 90, whereas rings 102 cause extra tension in rings 90. When therings 90 are of tungsten carbide, compressional forces are more suitableto the material. In the latter two embodiments the angles of thetrapezium are chosen to compensate for any difference between theco-efficients of thermal expansion of the material of the work rollrings and the material of the hollow shaft member.

Many advantages of the above described embodiment have already beengiven, but finally it should be noted in addition that the use ofcomposite work rolls which are radially loaded or axially loaded, orpreferably both, by a stressed hollow shaft member, leads to a stifferwork roll assembly (where stiffness means the deflection of a selectedpoint per unit load) than many of the assemblies in use at the presenttime.

The drawings have shown work rolls with rolling grooves. In applying theinvention to flat strip mills, the work rolls would have cylindricalrolling surfaces instead of the grooves.

I claim:

II. A method of manufacturing a rolling mill work roll assembly, saidassembly comprising a hollow shaft member which is co-axially secured toor formed integrally with a work roll drive shaft and which extendsco-axially in a bore of a work roll, said work roll including an annularmember formed. to define a rolling groove or surface of the work roll,said'method including applying a force axially to stretch said shaftmember to cause sufficient diametrical reduction thereof to permitinsertion thereof into its assembled position in said work roll bore,said shaft member when not so stretched having a diameter too large topermit such insertion, and removing said applied force to cause theshaft member to assume a stressed condition in which it exerts radialloading outwardly on said work roll to provide radial location of saidwork roll with respect to said shaft member.

2. A method as claimed in claim 1 wherein said applied force is removedto cause the shaft member to assume a stressed condition in which itcauses exertion of both radial loading outwardly on said work roll andaxially compressive loading between the axially opposite end faces ofthe work roll whereby to provide respectively radial location and axiallocation of said work roll with respect to said shaft member.

3. A method as claimed in claim 1 wherein said axial stretching force isapplied by hydraulic pressure means acting internally of said hollowshaft member.

4. A method of manufacturing a rolling mill work roll assembly, saidassembly comprising a hollow shaft member which is co-axially secured toor formed integrally with a work roll drive shaft and which extendsco-axially in a bore of a work roll, said work roll including an annularmember formed to define a rolling groove or surface of the work roll,said method including applying a force axially to stretch said shaftmember to cause sufficient diametrical reduction thereof to permitinsertion thereof into its assembled position in said work roll bore,said shaft member when not so stretched having a diameter too large topermit such insertion, providing first and second axial loading means inengagement with the respective axially opposite end faces of the annularmember while the hollow shaft member is in said inserted and stretchedcondition, and subsequently removing said applied force to cause thehollow shaft member to assume a stressed condition in whichsimultaneously the hollow shaft member exerts radial loading outwardlyon said work roll to provide radial location of said work roll withrespect to said hollow shaft member and said axial loading means exertaxially compressive loading between said axially opposite end faces ofthe work roll to provide axial location of said work roll with respectto said hollow shaft member.

1. A method of manufacturing a rolling mill work roll assembly, saidassembly comprising a hollow shaft member which is coaxially secured toor formed integrally with a work roll drive shaft and which extendsco-axially in a bore of a work roll, said work roll including an annularmember formed to define a rolling groove or surface of the work roll,said method including applying a force axially to stretch said shaftmember to cause sufficient diametrical reduction thereof to permitinsertion thereof into its assembled position in said work roll bore,said shaft member when not so stretched having a diameter too large topermit such insertion, and removing said applied force to cause theshaft member to assume a stressed condition in which it exerts radialloading outwardly on said work roll to provide radial location of saidwork roll with respect to said shaft member.
 2. A method as claimed inclaim 1 wherein said applied force is removed to cause the shaft memberto assume a stressed condition in which it causes exertiOn of bothradial loading outwardly on said work roll and axially compressiveloading between the axially opposite end faces of the work roll wherebyto provide respectively radial location and axial location of said workroll with respect to said shaft member.
 3. A method as claimed in claim1 wherein said axial stretching force is applied by hydraulic pressuremeans acting internally of said hollow shaft member.
 4. A method ofmanufacturing a rolling mill work roll assembly, said assemblycomprising a hollow shaft member which is co-axially secured to orformed integrally with a work roll drive shaft and which extendsco-axially in a bore of a work roll, said work roll including an annularmember formed to define a rolling groove or surface of the work roll,said method including applying a force axially to stretch said shaftmember to cause sufficient diametrical reduction thereof to permitinsertion thereof into its assembled position in said work roll bore,said shaft member when not so stretched having a diameter too large topermit such insertion, providing first and second axial loading means inengagement with the respective axially opposite end faces of the annularmember while the hollow shaft member is in said inserted and stretchedcondition, and subsequently removing said applied force to cause thehollow shaft member to assume a stressed condition in whichsimultaneously the hollow shaft member exerts radial loading outwardlyon said work roll to provide radial location of said work roll withrespect to said hollow shaft member and said axial loading means exertaxially compressive loading between said axially opposite end faces ofthe work roll to provide axial location of said work roll with respectto said hollow shaft member.